Russian tortoise (Testudo horsfieldii) is one of the most commonly kept in captivity species of reptiles. It is a reason for incorrect opinion that it is easy to maintain proper environment conditions and nutrition for it. The aim of the presented study was to investigate nutritional preferences of adult Russian tortoises kept in captivity. The scientific hypothesis was assumed that Russian tortoises select their feed sources. The experiment was carried out in free choice feeding model and lasted 6 weeks. In this time tortoises were fed with easy accessible and advised in literature groups of feed: fruits, vegetables and herbs. Each of them was used for 2 weeks. Nutritional preferences of tortoises were examined on the basis of the weight of remaining food. All used components were chemically analysed for dry matter, crude protein, crude fat, and crude fibre to find compound or nutrient which is key factor for its selection by tortoises. The results of the experiment confirm the hypothesis that Russian tortoises are selective in terms of feed choice. The main factor which affects their intake is water content in their fresh matter. It can be interpreted as the result of their evolutionary adaptation for dry environment and rare availability plants with high moisture in natural environment of these reptiles. Additionally, observation of many keepers that turtles prefer yellow and red colours of feed plants were confirmed.